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bcachefs: Fix short buffered writes

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In the buffered write path, we have to check for short writes that write
to the full page, where the page wasn't UpToDate; when this happens, the
page is partly garbage, so we have to zero it out and revert that part
of the write.

This check was wrong - we reverted total from copied, but didn't revert
the iov_iter, probably also leading to corrupted writes.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2020-07-09 13:54:58 -04:00 committed by Kent Overstreet
parent 0ba95acc44
commit 912bdf17a8
1 changed files with 11 additions and 10 deletions
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21
fs/bcachefs/fs-io.c
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@ -1454,23 +1454,23 @@ retry_reservation:
if (!pg_copied)
break;
if (!PageUptodate(page) &&
pg_copied != PAGE_SIZE &&
pos + copied + pg_copied < inode->v.i_size) {
zero_user(page, 0, PAGE_SIZE);
break;
}
flush_dcache_page(page);
copied += pg_copied;
if (pg_copied != pg_len)
break;
}
if (!copied)
goto out;
if (copied < len &&
((offset + copied) & (PAGE_SIZE - 1))) {
struct page *page = pages[(offset + copied) >> PAGE_SHIFT];
if (!PageUptodate(page)) {
zero_user(page, 0, PAGE_SIZE);
copied -= (offset + copied) & (PAGE_SIZE - 1);
}
}
spin_lock(&inode->v.i_lock);
if (pos + copied > inode->v.i_size)
i_size_write(&inode->v, pos + copied);
@ -1567,6 +1567,7 @@ again:
}
pos += ret;
written += ret;
ret = 0;
balance_dirty_pages_ratelimited(mapping);
} while (iov_iter_count(iter));